Classically, a cam follower comprises at least a tappet, a pin and a roller. The tappet extends along a longitudinal axis, while the pin and the roller are centered on a transverse axis. The tappet is formed with two lateral flanges, delimiting an intermediate gap between them and each comprising a cylindrical bore. The roller is positioned in the intermediate gap, between both flanges and bores. The pin is fitted in the two bores, such that the roller is movable in rotation relative to the pin around its axis. The pin may be caulked, in other words plastically deformed, on both opposite ends to create a mechanical connection by press-fit in the tappet bores.
When the cam follower is in service, the roller collaborates with a cam synchronized with the internal combustion engine camshaft. The rotation of the camshaft leads to a periodic displacement of a piston of the pump that rests against the tappet, to allow fuel to be delivered. The tappet is movable back and forth along the longitudinal axis in a bore belonging to the injection pump, with the cylindrical outer surface of the tappet sliding in this bore. The roller is movable in rotation around its central axis.
As shown by example in EP-A-2 607 636, it is known to provide the tappet with an external annular lubrication groove, perpendicular to the longitudinal axis, on the cylindrical outer surface of the tappet. The groove forms a lubricant reservoir to facilitate the sliding of the cam follower in the bore of the injection pump. For example, the lubricant used for the cam follower may be the oil used for the internal combustion engine for a motor vehicle.
The tappet is made in one part and is reworked by machining for producing the groove. The machining significantly increases the cost of manufacturing the cam follower.